Improvement in Photovoltaic Performance of Dye Sensitized Solar Cell Using Activated Carbon-TiO2 Composites-Based Photoanode

In this study, the activated carbon (AC) is synthesized from the oil fly ash (FA). Noncarbonaceous impurities were eliminated by acidic treatment of oil FA. Brunauer-Emmett-Teller and scanning electron microscopy energy-dispersive spectroscopy (SEM-EDS) analyses are used to characterize the AC. The AC is then mixed with TiO₂ in different concentrations to form hybrid photoanodes for dye sensitized solar cells. The dispersion of AC in TiO₂ is confirmed by transmission electron microscopy analysis. Solar cells are fabricated by employing the composite films as the working electrode. The UV-Visible absorption spectroscopy, photocurrent-voltage characteristic and electrochemical impedance spectroscopy analyses are carried out to examine the performance of solar cells. The results indicate that the concentration of AC in photoanode strongly affects the efficiency of solar cells. The solar cell fabricated with 0.05% AC -TiO₂ photoanode, shows the highest efficiency of 5.45%, which is 61% greater than unmodified photoanode (3.38%). Density functional theory quantum modeling technique is used to compute the band gap of TiO₂ and C-TiO₂ clusters.

I. Introduction

Burning of heavy fuel oil produces about 3 kg of ash per kl of oil [1], and most of the ashes (approximately 90%) are fly ash (FA). Heavy oil fly ash consists of inorganic substances such as silicon dioxide (SiO₂), iron oxide (Fe₂O₃), aluminum oxide (Al₂O ₃), and 70%–80% unburned carbon [2]. Owing to a high percentage of unburned carbon, FA can be used as an alternative raw material for activated carbon (AC) preparation. AC is a carbonaceous material having high porosity and an internal surface area [3]. The chemical and physical methods of activation of carbon allow the materials to produce surface area and a controlled distribution of pores that determine the electrode/electrolyte interface for photovoltaic applications (solar cells) [4], [5]. Carbon is being incorporated into the electrodes of photovoltaic devices as: electro-conductive additives, supports for active materials, electron transfer catalysts, intercalation hosts, and substrates for current leads [6]. For these reasons, carbon is of course also well suited as electrode materials for solar cells.